Forget the scale, the calorie counting, and forbidden foods. They may be doing more harm than good
While losing modest amounts of weight often lessens the impact of such health problems, so do regular exercise and healthful eating. "Even in heart disease, the role of fat tissue itself is small compared to the role of diet and exercise," says Linda Bacon, a nutrition professor at the University of California-Davis. "Since diet and exercise is the stuff that really matters, let's go after it directly and not use weight loss as the goal."
Fitness counts. Obesity, defined as a body mass index (a measure of height versus weight) over 30, does seem to increase mortality, but a study published last year in the Journal of the American Medical Association by the Centers for Disease Control and Prevention showed that increased deaths linked to obesity occur largely among those with BMIs over 35--people who carry an extra 50 or more pounds. The study revealed that Americans who are merely overweight--with BMIs between 25 and 30--actually live longer than people of normal weight. This may be due in part, the authors suggest, because new drugs to treat hypertension and cholesterol have reduced the negative impact of weight.
For years, research by Steven Blair, CEO of the Cooper Institute in Dallas, has shown that men and women who achieve a high level of fitness, regardless of weight, live longer and develop fewer chronic illnesses than thin people who aren't fit. It's also not clear that weight loss can make a heavy person's body the same as the body of a person who is naturally thin. Research on the role fat cells play and the impact of genes on weight gain, in fact, indicate that overweight bodies are never the same as naturally thin ones--no matter how much weight people lose.
Nevertheless, diets sell books, attract media attention, and fatten the wallets of authors who write them far more than they slim the bodies of the people who try them. Most popular diets seem to produce about the same modest weight loss. A study last year in JAMA looked at four such diets: Atkins (low carb), Ornish (low fat), Weight Watchers (low calorie), and the Zone (low glycemic load). Participants were randomly assigned to each diet. Only 50 to 65 percent of dieters stuck with the plans long enough to lose weight. But the ones who did lost between 4.6 and 7.3 pounds in a year and improved some of their cardiac risk factors, such as cholesterol levels. Michael Dansinger, an endocrinologist at the Tufts-New England Medical Center and lead researcher of the trial, calls the results "underwhelming."For her part, Karen Miller Kovach, chief scientific adviser for Weight Watchers, says "Weight Watchers has never preached diet alone as a means to lasting weight loss. But diet is part of the comprehensive lifestyle program."
Many experts were anxiously awaiting the first chapter in the Women's Health Initiative dietary modification study, probably the largest trial of a low-fat diet ever done, which was reported last week in the same journal. It showed that among more than 19,000 post-menopausal women, a low-fat, high-carbohydrate diet does not cause weight gain, as some low-carb enthusiasts have claimed. But it resulted in little long-term weight loss, either. Women in the study lost about 5 pounds the first year and kept off only about 1 pound over the seven years of the study.